Ephraim Littlefield's Connections to the Underbelly of Society

Ephraim Littlefield was a janitor at Harvard Medical School. He did the grunt work that no one else wanted to do, including buying cadavers from grave robbers. So if foul play has fallen on Dr. Parkman, which sounds like in all likelihood it has, he is dealing with grave robbers. But fundamentally, there has to be a reason for him to commit the homicide on Dr. parkman.